For many larger toner cartridges the filling rates are limited by the stability of toner replenishment to the filler hopper. When toner is passed through the toner filling line too fast the toner becomes fluid and causes problems such as over-filled cartridges, poor weight control, and free flow.
It is known to increase toner density by decreasing the amount of particle spacing air between the toner particles. As a result, currently filler hoppers are supplied by large bins in efforts to give the toner a long resident time in the bin so it will be delivered to the toner filling line with the toner density being increased. The increased toner density is equivalent to a reduced amount of particle spacing air between the toner particles.
Other methods to maintain delivery of dense toner to the toner filling line include utilizing various valves, vents, vibrators and mechanical agitators.